Fibrous cigarette filters



April 14, 1959 G'. P. TOUEY FIBROUS CIGARETTE FILTERS Filed March 3,1954 FIG 1 JTAIPCH PART/0.455

F/L TER WRAPPER TOBACCO FIG Z CIGARETTE WRAPPER R m H. F

ATTORNEYS P W w E R. 2% G w United States Patent FIBROUS CIGARETTEFILTERS George P. Touey, Kingsport, Tenn., assignor to Eastman KodakCompany, Rochester, N.Y., a corporation of New Jersey Application March3, 1954, Serial No. 413,950

7 Claims. (Cl. 131-408) The present invention relates to tobacco smokefiltering material and elements thereof suitable for use in cigarettes,pipes, cigarette holders, and cigar holders. More particularly, theinvention is concerned with an improvement in filters of the generaltype disclosed in US. Patents No. 2,794,239 and No. 2,794,480, bothissued June 4, 1957 to Crawford and Stevens.

In the aforementioned applications, newly discovered advantages of acertain type of fibrous tobacco smoke filter are discussed. The filteris prepared from a specially conditioned tow of synthetically spuncontinuous filaments and comprises a structurally unitary rod-like massof fibers and a wrapper encircling the mass, each fiber of the massbeing substantially co-extensive therewith, the fibers as a whole beingin substantial alignment longitudinally of the mass but substantiallyeach of the individual fibers having a plurality of short portionsthereof crimped into diverging and converging relationship to the mainfiber axis, a plurality of the fibers having surface solvation bonds tocontiguous fibers at random points of contact. Very good results havebeen obtained in the use of such filters for the removal of nicotine andtars from tobacco smoke, especially in view of the fact that the filterssupply other requirements equally as necessary to the success of atobacco smoke filter.

These filters also have a marked processing advantage over other filtersknown in the art. However, since the fibers in such filters are allparallel to each other, some channeling of the smoke through the filtermay be possible, resulting in a decreased'filtering action.

In other words, while interference with the smooth flow of combustionproducts through the channels is provided by the random bonds betweenadjacent fibers, by the incompleteness of fiber orientation, and by theshort fiber portions which are crimped into diverging and convergingrelationship to the main fiber axis, yet a certain amount of the smokein the core of any minute column of smoke passing through the filterapparently can escape a necessary minimum contact with the fibersurfaces. Experimental investigations have shown that any attempt toreduce the size of smoke channels through the filters by an increase infilter density either through greater compaction or through the use offiner fibers generally also results in an intolerable increase inpressure drop through the filter.

I now have found that the efiiciency of the filters described may besubstantially increased without equivalent increase in pressure dropthrough the filter by depositing certain finely divided solids in thesmoke channels provided by the spacing of adjacent fibers. I furtherhave discovered that when vegetable starch is employed as the finelydivided deposit, unusual efficiency is obtained.

This invention, therefore, has as one object the production of a moreefficient cigarette smoke filter consisting of a bundle of substantiallylongitudinally oriented textile fibers infused with finely dividedvegetable starch powders. Another object is to provide means forincreasing the efficiency of a cigarette filter prepared from ice atextile fiber. A still further object is provision of a filter which iscapable of removing nicotine, tars, and other deleterious components ofcigarette smoke without causing the smoke to be dry or distasteful.Another object is to increase the elficiency of tobacco smoke filters ofthe Crawford and Stevens application without creating a high pressuredrop. Other objects will be obvious from the present specification andclaims.

Accordingly, the present invention consists, in general, in a tobaccosmoke filtering medium comprising a mass of substantially longitudinallyaligned fibers, the spacing of substantially all groups of adjacentfibers providing minute passages for smoke therethrough, said masscarrying therein starch particles in an amount of 1 to 60% by weight ofthe mass and said particles occupying positions in and partiallyblocking said passages whereby a substantial portion of the smoke isimpinged either on the fibers or on the starch.

A more specific embodiment of the invention comprises a new tobaccosmoke filtering material of synthetically spun continuous filaments andan element made therefrom, the element comprising a structurally unitaryrod-like mass of fibers and a wrapper encircling the mass, each fiber ofthe mass being substantially coextensive therewith, the fibers as awhole being in substantial alignment longitudinally of the mass butsubstantially each of the individual fibers having a plurality of shortportions thereof crimped into diverging and converging relationship tothe main fiber axis, a plurality of the fibers having surface solvationbonds to contiguous fibers at random points of contact, the masscarrying substantially uniformly dispersed therein a solid finelydivided vegetable starch in the amount of 1 to 60% by weight of themass.

Most advantageously, the invention comprises a filter of celluloseacetate fibers having surface solvation bonds achieved through theapplication of a plasticizer spray, the filter carrying uniformlydispersed starch particles in the amount of about 10 to 40% by weight ofthe filter.

The invention is illustrated in the accompanying drawings in whichFigure 1 represents a magnified view of the interior of a mass offiltering material prepared in accordance with the invention, and

Figure 2 is a view of a cigarette having attached thereto a tip preparedfrom a filtering material of the invention.

Any suitable means known to the art for spreading a powder onto afibrous surface or through a fibrous mass may be employed in preparingfilters of the invention. Thus, for example, the starch powder can beblown onto the fibers or it can be applied as a slurry in cold water orin an organic solvent or plasticizer. Another method is to apply thestarch powder to the fibers electrostatically, i.e. to induce a chargeon the fibers by friction or other suitable means and then to run thefibers through a chamber containing highly concentrated starch dust.Still another method for applying the starch is to wet the surface ofthe fibers with an adhesive or a plasticizer before exposing them to apowder spraying device. Preferably, the starch is continuously appliedto an opened and banded moving tow formed as described in the Crawfordand Stevens applications. That is to say, tow from a supply roll isopened to debundlize the filaments and provide a larger and more uniformtow cross section, and the opened tow is spread uniformly to a muchlarger width of e.g., 7 times its original width, thereby exposingsubstantially all of the filaments to material, i.e. plasticizer,issuing from a dispenser under which the tow passes. The starch may beadded before, simultaneously with, or after the plasticizer, preferablywith or after.

Example 1 A partially opened tow of cellulose acetate yarn containingapproximately 20,000 fibers of five denier per filament was slowlypulled over a compressed air banding device as disclosed in theaforementioned Crawford and Stevens patent applications whichmomentarily spread out the fibers to a width of six inches. While thetow was in this spread condition it was sprayed with a highly agitatedslurry of one part of a commercial brand of powdered corn starch in fiveparts dimethoxyethylphthalate plasticizer. After this spreading andspraying treatment the tow was pulled back to its original shape of acord and fed into a conventional cigarette make-up machine which wrappedit with paper and cut it into rods similar in size to a standard sizecigarette. The rods contained 1 part starch, 5 parts plasticizer and 25parts cellulose acetate by weight. After the filter rods were given ashort heat treatment to cause partial solvation of the acetate fibers bythe plasticizer they were readily cut into 12 mm. filter tip lengths.These tips were attached to a standard brand of cigarettes available onthe retail market in the U.S. by means of an adhesive tape and thecigarettes were smoked on a smoking machine similar in design andoperation to the smoking machine described by J. A. Bradford, W. R.Harlan and H. R. Hanmer in Industrial and Engineering Chemistry, vol 28,pp. 836-9 (1936). The collected smoke was analyzed for nicotine andtars. The results of the smoking experiment were compared with thoseobtained from smoking the same brand of cigarettes containing 12 mm.filter tips made from the same tow of cellulose acetate fibersplasticized with dimethoxyethylphthalate without the ad- Moisture of thetobacco in each of the cigarettes=l1.8%. 1 Obtained from the collectedsmoke of ten filtered cigarettes.

Example 2 A loose, i.e. partially opened tow of cellulose acetate yarncontaining approximately 10,000 fibers of 8 denier per filament waspulled through a bath containing a highly agitated slurry of 15%commercially available starch powder in cold water. When dried, the towcontained 14% of starch by weight uniformly dispersed throughout. Thestarch impregnated tow was processed into filter rods according to themethod described in Example 1 and the rods were cut into 12 mm. lengths.tips so produced were attached to standard brand cigarettes and ten ofthese filter tipped cigarettes were smoked on the smoking machine. Thecollected smoke was analyzed for nicotine and tars. A control,consisting of the same brand of cigarettes tipped with filters made fromthe 8 denier per filament tow containing no starch was also smoked onthe smoking machine and the collected smoke was analyzed in the samemanner for nicotine and tars.

Moisture of the tobacco in each of the cigarettes=l2.l%.

Example 3 A tow of cellulose acetate yarn containing approxi- The filtermately 40,000 fibers of 3 denier per filament was spread out to a widthof six inches and sprayed with a 10% solution of a water-base adhesive.While the tow was still spread out and wet with the adhesive it wassprayed with a commercially available finely divided dry corn starchpowder and then rolled back into its original form. The impregnated towwas processed into filter rods and the rods were cut into 12 mm.lengths. The filter tips, containing 9% starch based on the weight ofthe acetate fibers, were attached to standard brand cigarettes and tenof these cigarettes were smoked onthe smoking machine.

mg. of mg. of

tars nicotine Acetate tow filter 19 Acetate tow filter containing 9%starch 98 13 Moisture oi the tobacco in each of the clgarettes=l2.0%.

In carrying out the operation of thisinvention the type of starchemployed is not a, critical factor. Rather, the form of the starch ismore important. The starch should be in a powdered form so that it canbe readily slurried' in a liquid or passed through a spraying nozzle.Any source of starch which passes this requirement can, there-' fore, beemployed. Such commercial starch powders as corn, wheat, potato, rice,and tapioca starch may be employed. Also, the oxidized starches may beused. In addition such starch derivatives as dextrin, and the variousforms of hydrolyzed starches may also be used.

While unusually good results have been obtained with filters preparedfrom a crimped continuous filament tow of cellulose acetate fiberssprayed with a plasticizer, e.g.' dimethoxyethyl phthalate ormethylphthalylethylglycollate, it will be recognized by those skilled inthe art that the usefulness of the invention extends to other fibrousfilters, including those prepared from fibers of viscose, cotton, nylon,polyamides, polyesters, etc., particularly where the fibers are insubstantial longitudinal alignment and are coextensive with the body ofthe filter.

I claim:

1. A tobacco smoke filter adapted to removecertain undesirablecomponents from tobacco smoke, said filter being comprised of a bundleof continuous, longitudinally aligned filaments in which substantiallyall of the filaments extend through the full length of the filter fromend to end, said filaments being essentially comprised of cellu loseacetate and a plasticizer therefor, said filaments carrying on theirsurface solid finely divided vegetable starch substantially uniformlydispersed over the surface ofthc filaments and a wrapper around thecircumeference of said bundle.

2. A filter in accordance with claim 1 wherein the bundle of filamentsis comprised of several thousand filaments of a denier per filament notgreater than 8.

3. A filter in accordance with claim 1 wherein the amount of plasticizerby weight is greater than the weight of the finely divided starch whichis uniformly dispersed on the filaments.

4. A filter in accordance with claim 1 wherein the plasticizer is anester.

5. A filter in accordance with claim 1 wherein the per centage by weightof the finely divided starch with re spect to the weight of thefilaments 'is from about 31% to 14%. i

6. A'filter in accordance with claim lxwherein the finely divided starchis rice starch. t

7. A tobacco smoke filter adapted to remove certain undesirablecomponents from tobacco smoke, said filter consisting essentially ofabundle of'at'ileast 10,000 longi' tudinally aligned syntheticthermoplastic filaments of a denier per filament less than 8 and inwhich substantially all the filaments extend through the full length ofthe filter from end to end, said filaments carrying a content of amaterial that will facilitate the bonding of a powdered solid to thefilaments, a content in the amount of from 10%40% by weight of thefilter of finely divided vegetable starch solid material substantiallyuniformly dispersed on the surface of the filaments, and a wrapperaround the circumference of said bundle.

References Cited in the file of this patent UNITED STATES PATENTS964,489 Campo July 19, 1910 1,809,529 Pettibone June 9, 1931 2,171,770Strauch Sept. 5, 1939 2,331,830 Garber Oct. 12, 1943 6 Browne et a1 July19, 1949 Francis Oct. 4, 1949 MacHenry Sept. 7, 1954 Taylor et al. May3, 1955 Von Reis et al. Oct. 25, 1955 Lieser Mar. 27, 1956 Jacobs et al.June 19, 1956 Knudsen Sept. 4, 1956 Hackney et a1 Dec. 18, 1956 Tayloret al Apr. 23, 1957 FOREIGN PATENTS Great Britain 1909 Australia Feb.25, 1954 Great Britain Dec. 24, 1935 Great Britain Aug. 7, 1941 GreatBritain Jan. 23, 1952 France Feb. 22, 1937

1. A TOBACCO SMOKE FILTER ADAPTED TO REMOVE CERTAIN UNDESIRABLECOMPONENTS FROM TOBACCO SMOKE, SAID FILTER BEING COMPRISED OF A BUNDLEOF CONTINUOUS, LONGITUDINALLY ALIGNED FILAMENTS IN WHICH SUBSTANTIALLYALL OF THE FILAMENTS EXTEND THROUGH THE FULL LENGTH OF THE FILTER FROMEND TO END, SAID FILAMENTS BEING ESSENTIALLY COMPRISED OF CELLULOSEACETATE AND A PLASTICIZER THEREFOR, SAID FILAMENTS CARRYING ON THEIRSURFACE SOLID FINELY DIVIDED VEGATABLE STARCH SUBSTANTIALLY UNIFORMLYDISPERSED OVER THE SURFACE OF THE FILAMENTS AND A WRAPPER AROUND THECIRCUMEFERENCE OF SAID BUNDLE.